diff --git a/Point_set_3/include/CGAL/Point_set_3/IO.h b/Point_set_3/include/CGAL/Point_set_3/IO.h
index c84d91c8477..735eb6f5116 100644
--- a/Point_set_3/include/CGAL/Point_set_3/IO.h
+++ b/Point_set_3/include/CGAL/Point_set_3/IO.h
@@ -295,19 +295,32 @@ read_off_point_set(
 
 
 #if (!defined(CGAL_CFG_NO_CPP0X_RVALUE_REFERENCE) && !defined(CGAL_CFG_NO_CPP0X_VARIADIC_TEMPLATES)) || defined(DOXYGEN_RUNNING)
+/// \cond SKIP_IN_MANUAL
+template <typename Point, typename Vector>
+bool
+read_ply_point_set(
+  std::istream& stream, ///< input stream.
+  CGAL::Point_set_3<Point, Vector>& point_set) ///< point set
+{
+  std::string dummy;
+  return read_ply_point_set (stream, point_set, dummy);
+}
+
+/// \endcond
 /*!
   \ingroup PkgPointSet3IO
+
+  The `comments` parameter can be omitted. If provided, it will be
+  used to store the potential comments found in the PLY
+  header. Each line starting by "comment " in the header is
+  appended to the `comments` string (without the "comment " word).
  */
 template <typename Point, typename Vector>
 bool
 read_ply_point_set(
   std::istream& stream, ///< input stream.
-#ifdef DOXYGEN_RUNNING
-  CGAL::Point_set_3<Point, Vector>& point_set) ///< point set
-#else
   CGAL::Point_set_3<Point, Vector>& point_set, ///< point set
-  std::string* comments = NULL) ///< recover PLY comments
-#endif
+  std::string& comments) ///< PLY comments.
 {
   if(!stream)
     {
@@ -324,8 +337,7 @@ read_ply_point_set(
     return false;
   }
 
-  if (comments != NULL)
-    *comments = reader.comments();
+  comments = reader.comments();
 
   for (std::size_t i = 0; i < reader.number_of_elements(); ++ i)
   {
@@ -358,17 +370,17 @@ read_ply_point_set(
   
 /*!
   \ingroup PkgPointSet3IO
+
+  If provided, the `comments` string is included line by line in
+  the header of the PLY stream (each line will be precedeed by
+  "comment ").
  */
 template <typename Point, typename Vector>
 bool
 write_ply_point_set(
   std::ostream& stream, ///< output stream.
-#ifdef DOXYGEN_RUNNING
-  const CGAL::Point_set_3<Point, Vector>& point_set)  ///< point set
-#else
-  const CGAL::Point_set_3<Point, Vector>& point_set,  ///< point set
-  std::string* comments = NULL) ///< write PLY comments
-#endif
+  const CGAL::Point_set_3<Point, Vector>& point_set,  ///< point set.
+  const std::string& comments = std::string()) ///< PLY comments.
 {
   typedef CGAL::Point_set_3<Point, Vector> Point_set;
   typedef typename Point_set::Index Index;
@@ -389,9 +401,9 @@ write_ply_point_set(
          << ((get_mode(stream) == IO::BINARY) ? "format binary_little_endian 1.0" : "format ascii 1.0") << std::endl
          << "comment Generated by the CGAL library" << std::endl;
 
-  if (comments != NULL)
+  if (comments != std::string())
   {
-    std::istringstream iss (*comments);
+    std::istringstream iss (comments);
     std::string line;
     while (getline(iss, line))
     {
diff --git a/Polyhedron/demo/Polyhedron/Scene_points_with_normal_item.cpp b/Polyhedron/demo/Polyhedron/Scene_points_with_normal_item.cpp
index bcf4b4c34fa..8c4c3484567 100644
--- a/Polyhedron/demo/Polyhedron/Scene_points_with_normal_item.cpp
+++ b/Polyhedron/demo/Polyhedron/Scene_points_with_normal_item.cpp
@@ -619,7 +619,7 @@ bool Scene_points_with_normal_item::read_ply_point_set(std::istream& stream)
   d->m_points->clear();
 
   bool ok = stream &&
-    CGAL::read_ply_point_set (stream, *(d->m_points), &(d->m_comments)) &&
+    CGAL::read_ply_point_set (stream, *(d->m_points), d->m_comments) &&
             !isEmpty();
     d->point_Slider->setValue(CGAL::Three::Three::getDefaultPointSize());
   std::cerr << d->m_points->info();
@@ -653,7 +653,7 @@ bool Scene_points_with_normal_item::write_ply_point_set(std::ostream& stream, bo
   if (binary)
     CGAL::set_binary_mode (stream);
 
-  CGAL::write_ply_point_set (stream, *(d->m_points), &(d->m_comments));
+  CGAL::write_ply_point_set (stream, *(d->m_points), d->m_comments);
 
   return true;
 }
diff --git a/Surface_mesh/include/CGAL/Surface_mesh/Surface_mesh.h b/Surface_mesh/include/CGAL/Surface_mesh/Surface_mesh.h
index 690a8818886..873d03929fd 100644
--- a/Surface_mesh/include/CGAL/Surface_mesh/Surface_mesh.h
+++ b/Surface_mesh/include/CGAL/Surface_mesh/Surface_mesh.h
@@ -2167,6 +2167,11 @@ private: //------------------------------------------------------- private data
   /// property with simple type: if they do, all edge properties with
   /// simple types are inserted in the stream. The halfedges follow
   /// the same behavior.
+  ///
+  /// If provided, the `comments` string is included line by line in
+  /// the header of the PLY stream (each line will be precedeed by
+  /// "comment ").
+  ///
   /// \relates Surface_mesh
   template <typename P>
   bool write_ply(std::ostream& os, const Surface_mesh<P>& sm, const std::string& comments = std::string())
@@ -2521,7 +2526,6 @@ private: //------------------------------------------------------- private data
   }
   /// \endcond
 
-  /// \relates Surface_mesh
   /// Extracts the surface mesh from an input stream in Ascii or
   /// Binary PLY format and appends it to the surface mesh `sm`.
   ///
@@ -2540,6 +2544,11 @@ private: //------------------------------------------------------- private data
   ///   added, where `[s]` is `v` for vertex and `f` for face, and
   ///   `[name]` is the name of PLY property.
   ///
+  /// The `comments` parameter can be omitted. If provided, it will be
+  /// used to store the potential comments found in the PLY
+  /// header. Each line starting by "comment " in the header is
+  /// appended to the `comments` string (without the "comment " word).
+  ///
   /// \pre The data in the stream must represent a two-manifold. If this is not the case
   ///      the `failbit` of `is` is set and the mesh cleared.
   /// \relates Surface_mesh